The invention relates generally to a vibration-suppressing device and, more particularly, to a mount assembly for use with a support mount connected to a support frame. In this type of vibration-proofing device, a vibrating component (e.g., an engine) is attached to a support mount, which connects the vibrating component via an elastic element to a machine element (typically a frame or sub-frame of an automobile). A spring-mounted inertial mass, capable of axially reciprocal motion by means of a drive so as to move in an opposite direction with respect to the vibrations of the vibrating component, is joined to the support mount by a spring.
A mount assembly of this general type is disclosed in German Published Application No. 34 23 698 (corresponding to U.S. Pat. No. 4,650,170, the contents of which are incorporated herein by reference). This patent discloses a vibration-damping mount for use with a vibrating object with a mount core and a thrust block, between which a spring element and a liquid-filled working space of a hydraulic damping device are arranged. The mount also has a compensation membrane, provided with an actuator, that covers at least 10% of the delimiting surface of the working space. The mount is connected to a control unit comprising a process computer that receives a reference input signal passed to it from the vibrating object by a signal transducer. This information is utilized in conjunction with a further signal characterizing the status of the element to create a control signal that directs the actuator to move in a manner that compensates for the pressure changes in the liquid caused by the vibrations. The control unit that is employed in this device rigidly couples the movements of the compensation membrane to the movements of the crankshaft, which, as a practical matter, is not an optimal approach.
German Patent No. 34 33 255 (which corresponds to U.S. Pat. No. 4,638,983, the contents of which are incorporated herein by reference) discloses an apparatus in which a hydraulically damped rubber mount is used to support a vibrating mechanical accessory on a sub-frame. An actuator having an electromagnetic drive that is associated with a liquid-filled working space connects the accessory to the sub-frame. The drive is linked to a control system employing both a signal taken from the vibrating mechanical accessory and a characteristics diagram to generate an actuation signal. This actuation signal is fed to a power amplifier, and thence to the actuator drive. In this device, the actuator is activated in a controlled fashion so that the vibrations caused by the mechanical accessory in two previously defined operating states are compensated for. To achieve this goal, the actuator is triggered by means of a characteristics diagram in which empirically determined reactions are stored as a function of a state variable of the mechanical accessory which describes its operating state. One such state variable, for example, may be the rotational speed of the crank shaft.
In the automotive field, this approach provides excellent isolation of vibrations that arise at certain rotational speeds and under certain load conditions. However, the spectrum of possible and actually occurring vibrations that result during real-world driving is not sufficiently covered by this approach. Furthermore, the determination of the necessary control data is very laborious.
There remains a need for the further development of a mount assembly of the aforesaid kind such that vibrations can be optimally compensated for in their entirety.